| Popis: |
Simple operational models predicting global irradiance from the visible channel of geostationary satellites are based on the observation that the relationship between planetary albedo [ie., normalized satellite count] and atmospheric transmissivity [ie., normalized global irradiance] is linear. Direct, diffuse irradiance and other solar radiation components are generally derived as a byproduct of global irradiance using transposition models, many of which have been developed for solar energy applications. The compounding of models reduces achievable precision. Ineichen and Perez (1999) recently introduced a one-step approach to model other solar components directly from the satellite counts This paper presents an initial validation of this one-step model against high quality hourly ground measurements in Albany, NY, covering a 9-month period. Results are compared to the traditional approach of compounding two models to derive direct and diffuse irradiance. The paper also investigates how readily, or potentially, available ancillary information (e.g., cloud cover from the National Weather Service) could lead to operational performance improvements. |
